“It’s very important as we set out on this journey that we are positive about the outcome.”

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Ex-Chancellor George Osborne has warned Britain should prioritise trade with the EU that cannot be made up in other trade deals

But the fresh Tory party civil war over Brexit deepened yesterday as George Osborne also waded to warn that leaving the EU’s single market could be the “biggest act of protectionism in British history”.

While insisting he wasn’t trying to “fight the last war”, the ex-Chancellor and mastermind of the failed Project Fear campaign insisted it was vital to keep free trade with “our biggest export market” and not walk away without any deal.

Osborne added: “No amount of trade deals with New Zealand are going to replace that we do at the moment with our big European neighbours”.